/*      $NetBSD: mcheck.c,v 1.2 2016/01/13 21:56:38 christos Exp $      */

/* Standard debugging hooks for `malloc'.
  Copyright 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
  Written May 1989 by Mike Haertel.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with this library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.

  The author may be reached (Email) at the address [email protected],
  or (US mail) as Mike Haertel c/o Free Software Foundation.  */

#ifndef _MALLOC_INTERNAL
#define _MALLOC_INTERNAL
#include <malloc.h>
#include <stdlib.h>
#include <stdio.h>
#endif

/* Old hook values.  */
static void (*old_free_hook) __P ((__ptr_t ptr));
static __ptr_t (*old_malloc_hook) __P ((__malloc_size_t size));
static __ptr_t (*old_realloc_hook) __P ((__ptr_t ptr, __malloc_size_t size));

/* Function to call when something awful happens.  */
static void (*abortfunc) __P ((enum mcheck_status));

/* Arbitrary magical numbers.  */
#define MAGICWORD       0xfedabeeb
#define MAGICFREE       0xd8675309
#define MAGICBYTE       ((char) 0xd7)
#define MALLOCFLOOD     ((char) 0x93)
#define FREEFLOOD       ((char) 0x95)

struct hdr
 {
   __malloc_size_t size;               /* Exact size requested by user.  */
   unsigned long int magic;    /* Magic number to check header integrity.  */
 };

#if     defined(_LIBC) || defined(STDC_HEADERS) || defined(USG)
#define flood memset
#else
static void flood __P ((__ptr_t, int, __malloc_size_t));
static void
flood (ptr, val, size)
    __ptr_t ptr;
    int val;
    __malloc_size_t size;
{
 char *cp = ptr;
 while (size--)
   *cp++ = val;
}
#endif

static enum mcheck_status checkhdr __P ((const struct hdr *));
static enum mcheck_status
checkhdr (hdr)
    const struct hdr *hdr;
{
 enum mcheck_status status;
 switch (hdr->magic)
   {
   default:
     status = MCHECK_HEAD;
     break;
   case MAGICFREE:
     status = MCHECK_FREE;
     break;
   case MAGICWORD:
     if (((char *) &hdr[1])[hdr->size] != MAGICBYTE)
       status = MCHECK_TAIL;
     else
       status = MCHECK_OK;
     break;
   }
 if (status != MCHECK_OK)
   (*abortfunc) (status);
 return status;
}

static void freehook __P ((__ptr_t));
static void
freehook (ptr)
    __ptr_t ptr;
{
 struct hdr *hdr = ((struct hdr *) ptr) - 1;
 checkhdr (hdr);
 hdr->magic = MAGICFREE;
 flood (ptr, FREEFLOOD, hdr->size);
 __free_hook = old_free_hook;
 free (hdr);
 __free_hook = freehook;
}

static __ptr_t mallochook __P ((__malloc_size_t));
static __ptr_t
mallochook (size)
    __malloc_size_t size;
{
 struct hdr *hdr;

 __malloc_hook = old_malloc_hook;
 hdr = (struct hdr *) malloc (sizeof (struct hdr) + size + 1);
 __malloc_hook = mallochook;
 if (hdr == NULL)
   return NULL;

 hdr->size = size;
 hdr->magic = MAGICWORD;
 ((char *) &hdr[1])[size] = MAGICBYTE;
 flood ((__ptr_t) (hdr + 1), MALLOCFLOOD, size);
 return (__ptr_t) (hdr + 1);
}

static __ptr_t reallochook __P ((__ptr_t, __malloc_size_t));
static __ptr_t
reallochook (ptr, size)
    __ptr_t ptr;
    __malloc_size_t size;
{
 struct hdr *hdr = ((struct hdr *) ptr) - 1;
 __malloc_size_t osize = hdr->size;

 checkhdr (hdr);
 if (size < osize)
   flood ((char *) ptr + size, FREEFLOOD, osize - size);
 __free_hook = old_free_hook;
 __malloc_hook = old_malloc_hook;
 __realloc_hook = old_realloc_hook;
 hdr = (struct hdr *) realloc ((__ptr_t) hdr, sizeof (struct hdr) + size + 1);
 __free_hook = freehook;
 __malloc_hook = mallochook;
 __realloc_hook = reallochook;
 if (hdr == NULL)
   return NULL;

 hdr->size = size;
 hdr->magic = MAGICWORD;
 ((char *) &hdr[1])[size] = MAGICBYTE;
 if (size > osize)
   flood ((char *) (hdr + 1) + osize, MALLOCFLOOD, size - osize);
 return (__ptr_t) (hdr + 1);
}

static void
mabort (status)
    enum mcheck_status status;
{
 const char *msg;
 switch (status)
   {
   case MCHECK_OK:
     msg = "memory is consistent, library is buggy";
     break;
   case MCHECK_HEAD:
     msg = "memory clobbered before allocated block";
     break;
   case MCHECK_TAIL:
     msg = "memory clobbered past end of allocated block";
     break;
   case MCHECK_FREE:
     msg = "block freed twice";
     break;
   default:
     msg = "bogus mcheck_status, library is buggy";
     break;
   }
#ifdef __GNU_LIBRARY__
 __libc_fatal (msg);
#else
 fprintf (stderr, "mcheck: %s\n", msg);
 fflush (stderr);
 abort ();
#endif
}

static int mcheck_used = 0;

int
mcheck (func)
    void (*func) __P ((enum mcheck_status));
{
 abortfunc = (func != NULL) ? func : &mabort;

 /* These hooks may not be safely inserted if malloc is already in use.  */
 if (!__malloc_initialized && !mcheck_used)
   {
     old_free_hook = __free_hook;
     __free_hook = freehook;
     old_malloc_hook = __malloc_hook;
     __malloc_hook = mallochook;
     old_realloc_hook = __realloc_hook;
     __realloc_hook = reallochook;
     mcheck_used = 1;
   }

 return mcheck_used ? 0 : -1;
}

enum mcheck_status
mprobe (__ptr_t ptr)
{
 return mcheck_used ? checkhdr (ptr) : MCHECK_DISABLED;
}

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